Indeed, a pooled analysis of 9 published studies determined that PD-L1 tumor cell staining ≥1% is associated with significantly higher clinical activity of anti-PD-1/PD-L1 monoclonal antibodies in pre-treated NSCLC patients, suggesting a potential role of PD-L1 expression as a predictive biomarker for the selection of patients to be treated with immune-checkpoint inhibitors [63]. The gene discussed is PDCD1; the disease is non-small cell lung carcinoma.